阅读说明：本技术 散热材、散热材的制造方法、组合物和发热体 (Heat radiating material, method for producing heat radiating material, composition, and heat generating body ) 是由 伊藤真纪 安藤拓司 竹泽由高 于 2018-10-04 设计创作，主要内容包括：一种散热材,包含金属粒子与树脂,且具有所述金属粒子偏向存在于至少一面侧的结构。(A heat dissipating material includes metal particles and a resin, and has a structure in which the metal particles are present in a biased manner on at least one surface side.)

1. A heat dissipating material includes metal particles and a resin, and has a structure in which the metal particles are present in a biased manner on at least one surface side.

2. The heat dissipating material according to claim 1, having a region in which the metal particles are present at a relatively high density on the at least one surface side.

3. The heat dissipating material according to claim 2, wherein the region is provided on a surface facing the heating element.

4. The heat dissipating material according to claim 2 or 3, which has the region on a side opposite to a surface facing the heating element.

5. The heat dissipating material according to any one of claims 2 to 4, wherein the thickness of the region is in a range of 0.1 μm to 100 μm.

6. The heat dissipating material according to any one of claims 2 to 5, wherein the ratio of the thickness of the region to the thickness of the entire heat dissipating material is in the range of 0.02% to 99%.

7. A heat sink includes metal particles and a resin, and the metal particles include metal particles arranged in a plane direction.

8. A heat dissipating material includes metal particles and a resin, and includes a layer having a concave-convex structure derived from the metal particles on a surface thereof.

9. A heat dissipating material comprising metal particles and a resin, and including a region 1 and a region 2 satisfying the following (A) and (B):

(A) the absorptivity of the electromagnetic wave under the wavelength of 2 mu m-6 mu m in the area 1 is more than the absorptivity of the electromagnetic wave under the wavelength of 2 mu m-6 mu m in the area 2; and

(B) the metal particle occupancy of region 1 > the metal particle occupancy of region 2.

10. A method for manufacturing a heat dissipating material, comprising: a step of forming a layer of a composition containing metal particles and a resin; and a step of allowing the metal particles in the layer to settle.

11. A method for manufacturing a heat dissipating material, comprising: disposing metal particles on a plane; and a step of forming a resin layer on the metal particles.

12. A method for manufacturing a heat dissipating material, comprising: a step of preparing a resin layer; and disposing metal particles on the resin layer.

13. A composition containing metal particles and a resin, for use in producing the heat dissipating material according to any one of claims 1 to 9.

14. A heat-generating body comprising the heat-dissipating material as recited in any one of claims 1 to 9.

Technical Field

The present invention relates to a heat dissipating material, a method for producing a heat dissipating material, a composition, and a heating element.

Background

In recent years, along with miniaturization and multi-functionalization of electronic devices, the amount of heat generated per unit area tends to increase. As a result, a hot spot (heat spot) in which heat is locally concentrated is generated in the electronic device, and problems such as a failure, a shortened lifetime, a reduction in operation stability, and a reduction in reliability of the electronic device occur. Therefore, it is increasingly important to release heat generated in the heat generating element to the outside to alleviate the occurrence of hot spots.

As a heat dissipation measure for electronic devices, a heat sink such as a metal plate or a heat sink is attached near a heat generating body of an electronic device, and heat generated in the heat generating body is conducted to the heat sink and dissipated to the outside. As a means for fixing the heat sink to the electronic device, a thermally conductive adhesive sheet (heat dissipating material) is used. For example, patent document 1 describes a heat dissipating material in which metal particles are embedded in a resin sheet in order to efficiently transfer heat generated in a heat generating component to a heat sink.

[ Prior art documents ]

[ patent document ]

Patent document 1: japanese patent laid-open No. 2000-129215

Disclosure of Invention

[ problems to be solved by the invention ]

The heat dissipating material described in patent document 1 achieves high heat conduction by embedding metal particles in a resin sheet, but since the range of heat diffusion is limited in the sheet, there is room for improvement in terms of improvement in heat dissipation performance.

In view of the above circumstances, an object of one aspect of the present invention is to provide a heat radiating material capable of efficiently radiating and transferring heat generated in a heat generating body, and a method for manufacturing the same. Another object of the present invention is to provide a composition for forming the heat dissipating material and a heat generating body provided with the heat dissipating material.

[ means for solving problems ]

Means for solving the problems include the following embodiments.

< 1 > a heat dissipating material comprising metal particles and a resin, wherein the metal particles are present in a biased manner on at least one surface side.

< 2 > the heat dissipating material according to < 1 > having a region where the metal particles are present at a relatively high density on the at least one surface side.

< 3 > the heat radiating member according to < 2 > having the region on a surface side facing the heating element.

< 4 > the heat radiating member according to < 2 > or < 3 > having the region on the side opposite to the surface facing the heating element.

< 5 > the heat dissipating material according to any one of < 2 > to < 4 >, wherein the thickness of the region is in the range of 0.1 μm to 100 μm.

< 6 > the heat dissipating material according to any one of < 2 > to < 5 > wherein the proportion of the thickness of the region in the thickness of the entire heat dissipating material is in the range of 0.02% to 99%.

< 7 > a heat dissipating material comprising metal particles and a resin, and the metal particles include metal particles arranged in a plane direction.

< 8 > a heat dissipating material comprising metal particles and a resin, and comprising a layer having a textured structure derived from the metal particles on the surface.

< 9 > a heat dissipating material comprising metal particles and a resin, and including a region 1 and a region 2 satisfying the following (A) and (B).

(A) The absorptivity of electromagnetic wave at wavelength of 2-6 μm in region 1 > the absorptivity of electromagnetic wave at wavelength of 2-6 μm in region 2

(B) Metal particle occupancy of region 1 > metal particle occupancy of region 2

< 10 > a method for producing a heat dissipating material, comprising: a step of forming a layer of a composition containing metal particles and a resin; and a step of allowing the metal particles in the layer to settle.

< 11 > a method for producing a heat dissipating material, comprising: disposing metal particles on a plane; and a step of forming a resin layer on the metal particles.

< 12 > a method for producing a heat dissipating material, comprising: a step of preparing a resin layer; and disposing metal particles on the resin layer.

< 13 > a composition containing metal particles and a resin, and used for producing a heat dissipating material according to any one of < 1 > to < 9 >.

< 14 > a heat-generating body comprising the heat-dissipating material according to any one of < 1 > to < 9 >.

[ Effect of the invention ]

According to an aspect of the present invention, there is provided a heat dissipating material capable of efficiently radiating and transferring heat generated in a heat generating body, and a method for manufacturing the same. According to another aspect of the present invention, there are provided a composition for forming the heat dissipating material and a heat generating body provided with the heat dissipating material.

Drawings

Fig. 1 is a schematic cross-sectional view of a sample produced in example 1.

Fig. 2 is an absorption wavelength spectrum of the sample produced in example 1.

Fig. 3 is a schematic cross-sectional view of the sample produced in example 2.

Fig. 4 is an absorption wavelength spectrum of the sample produced in example 2.

Fig. 5 is a schematic cross-sectional view of the sample produced in example 3.

Fig. 6 is an absorption wavelength spectrum of the sample produced in example 3.

Fig. 7 is a schematic cross-sectional view of the sample produced in example 4.

Fig. 8 is an absorption wavelength spectrum of the sample produced in comparative example 1.

Fig. 9 is an absorption wavelength spectrum of the sample produced in comparative example 2.

Fig. 10 is a schematic cross-sectional view of the sample produced in comparative example 3.

Fig. 11 is a schematic sectional view of an electronic device manufactured in embodiment 7.

Fig. 12 is a schematic sectional view of an electronic device manufactured in embodiment 8.

Fig. 13 is a schematic sectional view of a heat pipe (heat pipe) produced in example 9.

Detailed Description

Hereinafter, embodiments for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In the following embodiments, the constituent elements (including element steps) are not necessarily required unless otherwise specifically indicated. The same is true for numerical values and ranges thereof, and the invention is not limited thereto.

In the present disclosure, the term "step" includes a step that is independent from other steps, and also includes a step that is not clearly distinguished from other steps, as long as the purpose of the step is achieved.

In the present disclosure, numerical values before and after "to" are included in a numerical range represented by "to" are respectively a minimum value and a maximum value.

In the numerical ranges recited in the present disclosure, the upper limit or the lower limit recited in one numerical range may be replaced with the upper limit or the lower limit recited in another numerical range recited in a stepwise manner. In the numerical ranges disclosed in the present disclosure, the upper limit or the lower limit of the numerical range may be replaced with the values shown in the examples.

In the present disclosure, each ingredient may also contain a plurality of the corresponding substances. When a plurality of substances corresponding to each component are present in the composition, the content or content of each component refers to the total content or content of the plurality of substances present in the composition unless otherwise specified.

In the present disclosure, a plurality of particles corresponding to each component may also be included. When a plurality of particles corresponding to each component are present in the composition, the particle diameter of each component refers to a value related to a mixture of the plurality of particles present in the composition unless otherwise specified.

In the present disclosure, the term "layer" includes a case where the layer is formed only in a part of the region, in addition to a case where the layer is formed in the entire region when the layer is observed in the region.

In the present disclosure, when the embodiments are described with reference to the drawings, the configurations of the embodiments are not limited to the configurations shown in the drawings. The sizes of the members in the drawings are conceptual, and the relative relationship between the sizes of the members is not limited to this.

< Heat dissipating Material (first embodiment) >)

The heat dissipating material of the present embodiment is a heat dissipating material that includes metal particles and a resin, and has a structure in which the metal particles are present in a biased manner on at least one surface side.

The heat radiating member having the above-described structure exhibits an excellent heat radiating effect when attached to a heat generating body. The reason is not necessarily clear, but is considered as follows.

Since the metal particles contained in the heat dissipating material have a structure in which the metal particles are present in a biased manner on at least one surface side, a region (hereinafter, also referred to as a metal particle layer) in which the metal particles are present at a relatively high density is formed on at least one surface side. Consider that: the metal particle layer has a fine uneven structure on the surface thereof due to the shape of the metal particles, and when heat is transferred from the heating element to the metal particle layer, surface plasmon resonance occurs, and the wavelength region of the radiated electromagnetic wave changes. As a result, it is considered that: for example, the emissivity of electromagnetic waves in a wavelength region that is not absorbed by the resin contained in the heat radiating material is relatively increased, and heat storage by the resin is suppressed, thereby improving heat radiation.

In the heat dissipating material of the present embodiment, surface plasmon resonance is generated by forming a metal particle layer on at least one surface side. Therefore, surface plasmon resonance can be generated by a simple method, for example, compared to a method of forming a fine uneven structure by processing the surface of a metal plate and generating surface plasmon resonance.

The form of the metal particle layer is not particularly limited as long as it is in a state in which surface plasmon resonance can be generated. For example, a clear boundary may be formed between the metal particle layer and another region, or may not be formed. The metal particle layer may be present continuously or discontinuously (including in a pattern) in the heat dissipating material. The metal particles contained in the metal particle layer may be in contact with or not in contact with adjacent particles.

The thickness of the metal particle layer (the thickness of the portion having the smallest thickness when the thickness is not necessarily the same) is not particularly limited. For example, the thickness may be in the range of 0.1 μm to 100. mu.m. The thickness of the metal particle layer can be adjusted by, for example, the amount of metal particles contained in the metal particle layer, the size of the metal particles, and the like.

The ratio of the metal particle layer in the entire heat dissipating material is not particularly limited. For example, the ratio of the thickness of the metal particle layer to the thickness of the entire heat dissipating material may be in the range of 0.02% to 99%.

The density of the metal particles in the metal particle layer is not particularly limited as long as the metal particles are in a state in which surface plasmon resonance can be generated. For example, when the metal particle layer is observed from the front, the proportion of the metal particles in the observation surface is preferably 8% or more, more preferably 50% or more, further preferably 75% or more, and particularly preferably 90% on an area basis.

The scale can be calculated from the electron microscope image using image processing software, for example.

The position of the metal particle layer in the heat sink is not particularly limited as long as it is at least one surface side of the heat sink. For example, the heat sink may be located on the outermost surface of at least one surface of the heat sink, or may not be located on the outermost surface. The heat radiating member may be located on the side of the heat radiating member facing the heating element, or may be located on the side of the heat radiating member opposite the heating element.

In the present disclosure, "metal particles" mean particles in which at least a part of the surface is a metal, and the inside of the particles may be a metal or not a metal. The inside of the particle is preferably made of metal from the viewpoint of enhancing heat dissipation by heat conduction.

When at least a part of the surface of the metal particle is a metal, if an electromagnetic wave from the outside can reach the surface of the metal particle, the metal particle may be surrounded by a substance other than the metal, such as a resin or a metal oxide.

Examples of the metal contained in the metal particles include: copper, aluminum, nickel, iron, silver, gold, tin, titanium, chromium, palladium, and the like. The metal particles may contain only one kind of metal, or two or more kinds of metals. The metal may be a single body or an alloy.

The shape of the metal particles is not particularly limited as long as a desired uneven structure can be formed on the surface of the metal particle layer. Specific examples of the shape of the metal particles include: spherical, flake (flake), needle, rectangular parallelepiped, cubic, tetrahedral, hexahedral, polyhedral, tubular, hollow, three-dimensional needle-like structure extending in different 4-axis directions from the core portion, and the like. Of these, a spherical shape or a shape close to a spherical shape is preferable.

The size of the metal particles is not particularly limited. For example, the volume average particle diameter of the metal particles is preferably in the range of 0.1 to 30 μm. When the volume average particle diameter of the metal particles is 30 μm or less, infrared light contributing to heat dissipation tends to be sufficiently emitted. When the volume average particle diameter of the metal particles is 30 μm or less, electromagnetic waves (infrared light of a relatively low wavelength) contributing to improvement in heat dissipation tend to be sufficiently emitted. When the volume average particle diameter of the metal particles is 0.1 μm or more, the cohesive force of the metal particles is suppressed, and the metal particles tend to be easily arranged uniformly.

The volume average particle diameter of the metal particles may be set in consideration of the kind of the material other than the metal particles used for the heat dissipating material. For example, as the volume average particle diameter of the metal particles is smaller, the period of the uneven structure formed on the surface of the metal particle layer becomes smaller, and the wavelength at which the surface plasmon resonance generated in the metal particle layer is maximum becomes shorter. The absorption rate of the electromagnetic wave by the metal particle layer becomes maximum at the wavelength at which the surface plasmon resonance is maximum. Therefore, when the wavelength at which the surface plasmon resonance generated in the metal particle layer is maximum is shortened, the wavelength at which the metal particle layer has the maximum absorption rate of the electromagnetic wave is shortened, and the emissivity of the electromagnetic wave at the wavelength tends to be increased according to Kirchhoff's law. Therefore, by appropriately selecting the volume average particle diameter of the metal particles, the emission wavelength of the metal particle layer can be converted into a wavelength region that is difficult to be absorbed by the resin included in the heat dissipation material, and the heat dissipation property tends to be further improved.

The volume average particle diameter of the metal particles contained in the metal particle layer may be 10 μm or less, or 5 μm or less, or 3 μm or less. When the volume average particle diameter of the metal particles is in the above range, the wavelength region of the emitted electromagnetic wave can be converted into a low wavelength region (for example, 6 μm or less) in which the resin hardly absorbs the electromagnetic wave. This suppresses heat accumulation due to the resin, and improves heat dissipation.

In the present disclosure, the volume average particle diameter of the metal particles is a particle diameter (D50) when the cumulative particle diameter from the smaller diameter side becomes 50% in a volume-based particle size distribution curve obtained by a laser diffraction/scattering method.

From the viewpoint of effectively controlling the absorption wavelength or emission wavelength of the electromagnetic wave by the metal particle layer, the dispersion of the particle diameters of the metal particles contained in the metal particle layer is preferably small. By suppressing variation in the particle size of the metal particles, the following tendency is exhibited: a periodic uneven structure is easily formed on the surface of the metal particle layer, and surface plasmon resonance is easily generated.

Regarding the particle size variation of the metal particles, for example, when the particle size (D10) when the cumulative particle size from the small diameter side becomes 10% and the particle size (D90) when the cumulative particle size from the small diameter side becomes 90% are a (μm) and B (μm) in the volume-based particle size distribution curve, the a/B value is preferably about 0.3 or more, more preferably about 0.4 or more, and still more preferably about 0.6 or more.

The type of resin contained in the heat dissipating material is not particularly limited, and may be selected from known thermosetting resins, thermoplastic resins, ultraviolet-curable resins, and the like. Specifically, there may be mentioned: phenol resins, alkyd resins, aminoalkyd resins, urea resins, silicone resins, melamine urea resins, epoxy resins, polyurethane resins, unsaturated polyester resins, vinyl acetate resins, acrylic resins, chlorinated rubber-based resins, vinyl chloride resins, fluorine resins, and the like. Among these, acrylic resins, unsaturated polyester resins, epoxy resins, and the like are preferable from the viewpoints of heat resistance, acquisition properties, and the like. The metal particle layer may contain only one kind of resin, or two or more kinds of resins.

The heat dissipating material may include materials other than resin and metal particles. For example, ceramic particles, additives, and the like may also be included.

The heat sink includes ceramic particles, for example, which can further improve the heat dissipation effect of the heat sink. Specific examples of the ceramic particles include: particles of boron nitride, aluminum oxide, magnesium oxide, titanium oxide, zirconium oxide, iron oxide, copper oxide, nickel oxide, cobalt oxide, lithium oxide, silicon dioxide, and the like. The metal particle layer may contain only one kind of ceramic particles, or two or more kinds of ceramic particles. The surface may be covered with a coating film containing a resin, an oxide, or the like.

The size and shape of the ceramic particles are not particularly limited. For example, the metal particles may be the same as those described as the preferable form of the size and shape of the metal particles.

By including an additive in the heat dissipating material, a desired function can be imparted to the heat dissipating material or the material for forming the heat dissipating material. Specific examples of the additives include: dispersants, film-forming aids, plasticizers, pigments, silane coupling agents, viscosity modifiers, and the like.

The shape of the heat dissipating material is not particularly limited, and may be selected according to the application. Examples thereof include: sheet, film, plate, etc. Alternatively, the heat radiating material may be applied to the heating element to form a layer.

The thickness of the heat dissipating material (the thickness of the portion having the smallest thickness when the thickness is not necessarily the same) is not particularly limited. For example, it is preferably in the range of 1 μm to 500. mu.m, and more preferably 10 μm to 200. mu.m. If the thickness of the heat dissipating material is 500 μm or less, the heat dissipating material is less likely to be a heat insulating layer, and good heat dissipation tends to be maintained. When the thickness of the heat dissipating material is 1 μm or more, the function of the heat dissipating material tends to be sufficiently obtained.

The wavelength region of the electromagnetic wave absorbed or emitted by the heat dissipating material is not particularly limited, and from the viewpoint of thermal radioactivity, the absorptance or emissivity of the electromagnetic wave for each wavelength of 2 μm to 20 μm is preferably 0.8 or more, and is more preferably as close to 1.0, and even more preferably.

The absorption rate of electromagnetic waves can be measured by a fourier transform infrared spectrophotometer. According to the kirschhoff's law, the absorption rate and emission rate of electromagnetic waves are considered to be equal.

The wavelength region of the electromagnetic wave absorbed by the heat dissipating material can be measured by a fourier transform infrared spectrophotometer. Specifically, the transmittance and reflectance at each wavelength can be measured and calculated by the following formulas.

Absorption (emissivity) 1-transmittance-reflectance

The use of the heat dissipating material is not particularly limited. For example, the heat generating element may be attached to a portion of the electronic device corresponding to the heat generating element to radiate heat generated by the heat generating element. In addition, the present invention can also be used for a heat sink that transfers heat generated in a heat generating element to a metal plate, a heat sink, or the like.

< Heat dissipating Material (second embodiment) >)

The heat dissipating material of the present embodiment is a heat dissipating material including metal particles and a resin, and the metal particles include metal particles arranged in a plane direction.

The heat radiating member having the above-described structure exhibits an excellent heat radiating effect when attached to a heat generating body. The reason is not necessarily clear, but is considered as follows.

The heat dissipating material having such a structure contains metal particles arranged in a plane direction (a direction perpendicular to a thickness direction). With respect to these metal particles, it is considered that: a layer (metal particle layer) having a fine uneven structure is formed along the surface direction of the heat sink, and when heat is transferred from the heating element, surface plasmon resonance occurs, and the wavelength region of the radiated electromagnetic wave changes. As a result, it is considered that: for example, the emissivity of electromagnetic waves in a wavelength region that is not absorbed by the resin contained in the heat radiating material is relatively increased, and heat storage by the resin is suppressed, thereby improving heat radiation.

< Heat dissipating Material (third embodiment) >)

The heat dissipating material of the present embodiment includes metal particles and a resin, and includes a layer having an uneven structure derived from the metal particles on a surface thereof.

The heat radiating member having the above-described structure exhibits an excellent heat radiating effect when attached to a heat generating body. The reason is not necessarily clear, but is considered as follows.

The heat dissipating material having such a structure includes a layer (metal particle layer) having an uneven structure on the surface thereof due to the shape of the metal particles. Consider that: when heat is transferred from the heating element to the metal particle layer, surface plasmon resonance occurs, and the wavelength region of the emitted electromagnetic wave changes. As a result, it is considered that: for example, the emissivity of electromagnetic waves in a wavelength region that is not absorbed by the resin contained in the heat radiating material is relatively increased, and heat storage by the resin is suppressed, thereby improving heat radiation.

< Heat dissipating Material (fourth embodiment) >)

The heat dissipating material of the present embodiment includes metal particles and a resin, and includes a region 1 and a region 2 satisfying the following (a) and (B).

(A) The absorptivity of electromagnetic wave at wavelength of 2-6 μm in region 1 > the absorptivity of electromagnetic wave at wavelength of 2-6 μm in region 2

(B) Metal particle occupancy of region 1 > metal particle occupancy of region 2

The heat radiating member having the above-described structure exhibits an excellent heat radiating effect when attached to a heat generating body. The reason is not necessarily clear, but is considered as follows.

Resins generally have properties that are difficult to absorb short-wavelength infrared light and easy to absorb long-wavelength infrared light. It is therefore assumed that: by increasing the absorption rate (i.e., increasing the emissivity) of electromagnetic waves in a wavelength region of 2 to 6 μm, which is difficult to be absorbed by the resin, heat storage by the resin is suppressed, and the heat dissipation is improved.

The heat dissipation material having the above-described structure includes region 1 having a higher absorptivity of electromagnetic waves in a wavelength region of 2 to 6 μm than region 2, thereby solving the above-described problem.

As the region 1, specifically, there can be mentioned: the metal particle layer is configured to have a fine uneven structure formed by metal particles by containing a relatively large amount of metal particles, and to generate a surface plasmon resonance effect. As the region 2, specifically, there can be mentioned: a resin layer containing a relatively large amount of resin. Regions 1 and 2 may also be: one of them is disposed on the side of the heat radiating member facing the heating element, and the other is disposed on the side opposite to the side facing the heating element.

In the above structure, the "metal particle occupancy" refers to a volume-based proportion of the metal particles in the region. The "electromagnetic wave absorptance" can be measured in the same manner as the absorptance of the electromagnetic wave of the heat radiating material.

The specific structure of the heat dissipating material of each of the above embodiments, the details and preferred forms of the metal particles and the resin contained in the heat dissipating material, and the like can be applied to each of the embodiments.

< method for manufacturing Heat sink (first embodiment) >)

The method for manufacturing a heat dissipating material according to the present embodiment includes: a step of forming a layer (composition layer) of a composition containing metal particles and a resin; and a step of allowing the metal particles in the layer to settle.

According to the method, the heat dissipation material can be manufactured.

In the above method, the method of carrying out the step of forming the layer (composition layer) of the composition containing the metal particles and the resin is not particularly limited. For example, the composition may be applied to a substrate arranged so that the main surface thereof is horizontal, to have a desired thickness.

The base material of the coating composition may or may not be removed after the heat dissipating material is produced or before the heat dissipating material is used. The latter case includes a case where the composition is directly applied to an object (heat generating body) to which the heat radiating material is attached. The method for applying the composition is not particularly limited, and known methods such as brush coating, spray coating, roll coater coating, and dip coating can be used. Electrostatic coating, curtain coating, electro coating, powder coating, and the like may be used depending on the object to be coated.

Among the methods, a method of performing the step of settling the metal particles in the composition layer is not particularly limited. For example, the composition may be left until the metal particles in the composition layer formed on the substrate arranged so that the main surface becomes horizontal naturally settle. From the viewpoint of promoting the sedimentation of the metal particles in the composition layer, it is preferable that a > B is satisfied when the density (mass per unit volume) of the metal particles is a and the density of the component other than the metal particles is B.

If necessary, in the above method, after the step of allowing the metal particles in the composition layer to settle, the resin may be subjected to a treatment such as drying, baking, or hardening.

The kind of the metal particles and the resin contained in the composition is not particularly limited. For example, the metal particles and the resin contained in the heat dissipating material may be selected. In addition, other materials that can be included in the heat dissipation material may also be included.

The composition may be in the form of a dispersion (such as an aqueous emulsion) containing a solvent, a varnish, or the like, as required. The solvent contained in the composition includes water and an organic solvent, and is preferably selected in consideration of combination with other materials such as metal particles and resins contained in the composition. As the organic solvent, there may be mentioned: organic solvents such as ketone solvents, alcohol solvents, and aromatic solvents. More specifically, there may be mentioned: methyl ethyl ketone, cyclohexene, ethylene glycol, propylene glycol, methanol, isopropanol, butanol, benzene, toluene, xylene, ethyl acetate, butyl acetate, and the like. The solvent may be used alone or in combination of two or more.

The details and preferred form of the heat dissipating material produced by the method may be the same as those of the heat dissipating material, for example.

< method for manufacturing Heat sink (second embodiment) >)

The method for manufacturing a heat dissipating material according to the present embodiment includes: disposing metal particles on a plane; and a step of forming a resin layer on the metal particles.

According to the method, the heat dissipation material can be manufactured.

Among the methods, a method of performing the step of disposing the metal particles on the plane is not particularly limited. For example, the metal particles may be spread on a substrate arranged so that the main surface becomes horizontal.

Among the methods, a method of performing the step of forming the resin layer on the metal particles is not particularly limited. For example, a resin molded into a sheet shape may be disposed on the metal particles, or a resin having fluidity may be coated on the metal particles. In this case, the resin layer is preferably formed so that a part of the resin is present between the metal particles.

If necessary, after the step of forming the resin layer on the metal particles, a treatment such as drying, baking, or curing of the resin may be performed.

The kind of the metal particles and the resin used in the method is not particularly limited. For example, the metal particles and the resin contained in the heat dissipating material may be selected. In addition, other materials that can be included in the heat dissipation material may also be included. Furthermore, the solvent used in the method of the first embodiment may be contained.

The details and preferred form of the heat dissipating material produced by the method may be the same as those of the heat dissipating material, for example.

< method for manufacturing Heat sink (third embodiment) >)

The method for manufacturing a heat dissipating material according to the present embodiment includes: a step of preparing a resin layer; and disposing metal particles on the resin layer.

According to the method, the heat dissipation material can be manufactured.

Among the methods, a method of performing the step of preparing the resin layer is not particularly limited. For example, a resin having fluidity may be applied to a substrate, or a resin molded into a sheet may be used. In the case of using a resin molded into a sheet shape, the lamination process may be performed while evacuating so as not to generate a gap between the metal particles and the resin.

Among the above methods, a method of performing the step of disposing the metal particles on the resin layer is not particularly limited. For example, it can be performed as follows: the resin layer is filled with metal particles in a state where the resin layer is disposed so that the main surface thereof is horizontal. In this case, the metal particles are preferably disposed so as to be embedded in the resin layer.

If necessary, after the step of disposing the metal particles on the resin layer, the resin may be subjected to a treatment such as drying, baking, or curing.

The kind of the metal particles and the resin used in the method is not particularly limited. For example, the metal particles and the resin contained in the heat dissipating material may be selected. In addition, other materials that can be included in the heat dissipation material may also be included. Furthermore, the solvent used in the method of the first embodiment may be contained.

The details and preferred form of the heat dissipating material produced by the method may be the same as those of the heat dissipating material, for example.

< composition >

The composition of the present embodiment is a composition for producing the heat dissipating material, which contains metal particles and a resin.

The details and preferred forms of the metal particles, the resin and other components contained in the composition are the same as those described in the heat radiating material and the method for producing the same.

The ratio of the metal particles to the resin in the composition is not particularly limited. For example, the mass-based ratio (metal particles: resin) may be 0.1: 99.9-99.9: in the range of 0.1, it may be 1: 99-50: 50, or less.

In the case where the composition is used in the method for producing a heat dissipating material according to the first embodiment, it is preferable that the relationship of a > B is satisfied when the density (mass per unit volume) of the metal particles is a and the density of the component other than the metal particles is B, from the viewpoint of promoting the sedimentation of the metal particles in the composition.

< heating element >

The heat generating body of the present embodiment is provided with the heat radiating material of the above-described embodiment.

The kind of the heating element is not particularly limited. Examples thereof include: an Integrated Circuit (IC) included in an electronic device, an electronic component such as a semiconductor element, a heat pipe, and the like.

The form of mounting the heat radiating member on the heating element is not particularly limited. For example, the adhesive heat dissipating material may be directly attached, or may be attached via an adhesive material or the like. Alternatively, a heat radiating material layer may be formed by applying a heat radiating material to the heating element.

When the heat radiating member is attached to the heating element, the heating element may be attached so that the side of the heat radiating member where the metal particle layer is located is in contact with the heating element, or the heating element may be attached so that the side of the heat radiating member opposite to the side where the metal particle layer is located is in contact with the heating element.

The heat generating body may also include a heat sink, if necessary. In this case, the heat radiating member is preferably interposed between the main body of the heating element and the heat sink. The heat radiating material is interposed between the main body of the heating element and the heat sink, thereby achieving excellent heat radiation. Examples of the heat sink include: plates, heat sinks, etc., comprising metals such as aluminum, iron, copper, etc.

The part of the main body where the heat dissipation material is installed may be a plane or may not be a plane. In the case where the portion of the body to which the heat dissipating material is attached is not flat, the heat dissipating material may be attached using a flexible heat dissipating material.

[ examples ]

Hereinafter, the present disclosure will be described in further detail with reference to examples. However, the present disclosure is not limited to the contents described in the following examples.

< example 1 >

99.13% by volume of an acrylic resin, 0.87% by volume of copper particles (volume average particle diameter: 2 μm), and 30% by mass of butyl acetate with respect to 100% by mass of the total of the two components were placed in a vessel and mixed by a hybrid mixer (hybrid mixer) to prepare a composition. The composition was spray-coated on the entire surface of an aluminum plate 100mm × 100mm and 1mm thick by using a spray coating apparatus to form a composition layer. The composition layer was allowed to dry naturally, and was cured by heating at 60 ℃ for 30 minutes to prepare a sample having a film thickness of 30 μm.

Fig. 1 schematically shows a cross-sectional view of the sample thus produced. As shown in fig. 1, sample 1 includes copper particles 11 and a resin 12, and has a structure in which copper particles 11 are aggregated on the aluminum plate 13 side to form a metal particle layer. The reason for this is that: since the density of the copper particles contained in the composition is higher than the density of the components other than the copper particles in the composition, the copper particles settle in the composition layer.

The distances in space between the settled copper particles were measured from the images obtained from the optical microscope, and as a result, the average distance (the arithmetic average of the distances measured for arbitrarily selected 100 particles) was 1 μm.

The heat emissivity of the prepared sample was measured at room temperature (25 ℃) using an emissivity measuring instrument (D and (and) S AERD manufactured by Kyoto electronics industries) (measurement wavelength region: 3 μm to 30 μm).

The emissivity of the sample of example 1 was 0.9.

The absorption wavelength spectrum of the sample thus produced was examined by a fourier transform infrared spectrophotometer. The obtained absorption wavelength spectrum is shown in fig. 2. It was confirmed that the absorption efficiency was particularly increased in the wavelength region of 10 μm or less, as compared with the sample (containing no metal particles) of comparative example 1 described later.

< example 2 >

A composition was prepared by placing 96.5 vol% of an acrylic resin, 3.5 vol% of copper particles (volume average particle diameter 8 μm), and 30 mass% of butyl acetate with respect to 100 mass% of the total of the two components in a container and mixing them with a mixer. The composition is applied to a substrate arranged so that the main surface thereof becomes horizontal by using an applicator (bar coater), thereby forming a composition layer. The composition layer was allowed to dry naturally, and was cured by heating at 60 ℃ for 30 minutes to prepare a sample having a film thickness of 30 μm. Then, the sample was peeled off from the substrate, and the surface opposite to the side from which the substrate was peeled was attached to an aluminum plate of 100mm × 100mm and 1mm in thickness.

Fig. 3 schematically shows a cross-sectional view of the sample thus produced. As shown in fig. 3, sample 1 includes copper particles 11 and a resin 12, and has a structure in which copper particles 11 are collected on the surface side opposite to aluminum plate 13 to form a metal particle layer. The reason for this is that: the sample in which the copper particles were settled down to the substrate side in the composition layer was attached to an aluminum plate on the side opposite to the side to which the substrate was attached. The average distance between the settled copper particles was measured in the same manner as in example 1, and the result was 4 μm.

The emissivity of the sample of example 2 measured in the same manner as in example 1 was 0.86.

Fig. 4 shows an absorption wavelength spectrum obtained in the same manner as in example 1. It was confirmed that the absorption efficiency was particularly increased in the wavelength region of 2 μm to 7 μm as compared with the sample (containing no metal particles) of comparative example 1 described later.

< example 3 >

A composition was prepared by placing 96.5 vol% of an acrylic resin, 3.5 vol% of aluminum particles (volume average particle diameter 2 μm), and 30 mass% of butyl acetate with respect to 100 mass% of the total of the two components in a container and mixing them with a mixer. The composition is applied to a substrate arranged so that the main surface thereof becomes horizontal by using an applicator (bar coater), thereby forming a composition layer. The composition layer was allowed to dry naturally, and was cured by heating at 60 ℃ for 30 minutes to prepare a sample having a film thickness of 30 μm. Then, the sample was peeled off from the substrate, and the surface opposite to the side from which the substrate was peeled was attached to an aluminum plate of 100mm × 100mm and 1mm in thickness.

Fig. 5 shows a schematic cross-sectional view of the sample thus produced. As shown in fig. 5, sample 1 includes aluminum particles 11 and a resin 12, and has a structure in which aluminum particles 11 are collected on the surface side opposite to aluminum plate 13 to form a metal particle layer.

In the sample of example 3, the amount of the metal particles in the composition was larger than that in example 1, and therefore the intervals between the metal particles were narrow, and there was a portion where the metal particles overlapped when viewed in the thickness direction of the sample. Fig. 5 schematically shows a state where the metal particles are three-layered, but the metal particles are not limited to three-layered, and may be arranged in two-layered, or may be arranged in a plurality of layers of two or more layers.

Fig. 6 shows an absorption wavelength spectrum obtained in the same manner as in example 1. Compared with the sample of example 2, it was confirmed that: the absorption efficiency was higher in the wavelength region of 2 μm to 8 μm than in example 2, and lower in the wavelength region of 10 μm to 20 μm than in example 2. Therefore, infrared rays that transmit through the wavelength region of the resin can be selectively emitted as compared with the sample (without metal particles) of comparative example 1 described later.

< example 4 >

99.13% by volume of an acrylic resin, 0.87% by volume of a coating film (having a film thickness of 0.5 μm) having an acrylic resin as a spacer (spacer) provided around aluminum particles (having a volume average particle diameter of 2 μm) to adjust the particle spacing to a constant value, and 30% by mass of butyl acetate with respect to 100% by mass of the total of the two components were placed in a container and mixed by a mixer to prepare a composition. The composition was spray-coated on an aluminum plate 100mm × 100mm and 1mm thick using a spray coating apparatus to form a composition layer. The composition layer was allowed to dry naturally, and was cured by heating at 60 ℃ for 30 minutes to prepare a sample having a film thickness of 30 μm.

Fig. 7 shows a schematic cross-sectional view of the sample thus produced. As shown in fig. 7, sample 1 includes aluminum particles 11 and a resin 12 having a resin film 14 around them, and has a structure in which aluminum particles 11 are collected on the aluminum plate 13 side to form a metal particle layer. The average distance between the aluminum particles 11 (excluding the resin film portion) was adjusted to 1 μm by the resin film 14.

The emissivity of the sample of example 4 measured in the same manner as in example 1 was 0.9.

The absorption wavelength spectrum of the sample of example 4 becomes the same as that shown in fig. 2.

< example 5 >

A sample having a film thickness of 30 μm was produced in the same manner as in example 1, except that the amount of copper particles was changed to equal amounts (volume average particle diameter: 1 μm).

< example 6 >

A sample having a film thickness of 100 μm was prepared from the same composition as in example 5.

< comparative example 1 >

A composition having an adjusted viscosity was prepared by mixing 30 mass% of butyl acetate with respect to 100 mass% of an acrylic resin. The composition was spray-coated on the entire surface of an aluminum plate 100mm × 100mm and 1mm thick by using a spray coating apparatus to form a composition layer. The composition layer was allowed to dry naturally, and was cured by heating at 60 ℃ for 30 minutes to prepare a sample having a film thickness of 30 μm.

The emissivity of the sample of comparative example 1 measured in the same manner as in example 1 was 0.7.

Fig. 8 shows an absorption wavelength spectrum obtained in the same manner as in example 1.

< comparative example 2 >

The same composition as in comparative example 1 was spray-coated onto the entire surface of an aluminum plate 100mm × 100mm and 1mm thick by using a spray coating apparatus to form a composition layer. The composition layer was allowed to dry naturally, and was cured by heating at 60 ℃ for 30 minutes to prepare a sample having a film thickness of 100 μm.

The emissivity of the sample of comparative example 2 measured in the same manner as in example 1 was 0.9.

Fig. 9 shows an absorption wavelength spectrum obtained in the same manner as in example 1. It is understood that the thickness of the sample is increased as compared with the sample of comparative example 1, and thus the absorption efficiency in the wavelength region of 8 μm or more is increased, and the emissivity is higher than that of comparative example 1.

< comparative example 3 >

A commercially available thermal radioactive coating material comprising 95 vol% of an acrylic resin and 5 vol% of silica particles (volume average particle diameter: 2 μm) was spray-coated on an aluminum plate 100mm X100 mm and 1mm in thickness by using a spray coating apparatus to form a composition layer. The composition layer was allowed to dry naturally, and was cured by heating at 60 ℃ for 30 minutes to prepare a sample having a film thickness of 30 μm.

Fig. 10 shows a schematic cross-sectional view of the sample thus produced. As shown in fig. 10, sample 1 includes silica particles 11 and a resin 12, and has a structure in which the silica particles 11 are not aggregated on the aluminum plate 13 side but dispersed in the resin 12.

The emissivity of the sample of comparative example 3 measured in the same manner as in example 1 was 0.81.

The compositions prepared in examples and comparative examples were used to evaluate heat dissipation properties by the following methods. The results are shown in table 1.

A commercially available sheet heating element (polyimide heater) was sandwiched between aluminum plates (50 mm. times.80 mm, thickness: 2 mm). The K thermocouple was attached to the surface of the aluminum plate using aluminum solder. The composition was applied to the entire surface of both sides of one of the aluminum plates and allowed to dry naturally, to prepare a sample having a thickness of 30 μm. The aluminum plate on which the sample was formed was set at the center of a thermostatic bath set at 25 ℃, and the temperature change of the surface of the aluminum plate was measured. At this time, the output of the heater was set so that the surface temperature of the aluminum plate in a state where no sample was formed became 100 ℃. Since the heater generates a certain amount of heat, the higher the heat dissipation effect of the sample, the lower the temperature of the aluminum plate surface. That is, it can be said that the lower the surface temperature of the aluminum plate, the higher the heat radiation effect. The measured surface temperature (maximum temperature) of the aluminum plate is shown in table 1.

[ Table 1]

As shown in table 1, in comparative examples 1 and 2 in which the samples including only the resin were mounted, the surface temperature of the aluminum plate was reduced to 85 ℃ and 80 ℃ as compared with the surface temperature of the aluminum plate in which the sample was not mounted, but the reduction effect was small as compared with the examples. The reason is considered to be that: the sample does not include the metal particle layer, and therefore, the heat dissipation effect by the heat radiation heat transfer is smaller than that of the embodiment.

In comparative example 3 in which the sample having the structure in which the silica particles are dispersed in the resin was mounted, the surface temperature of the aluminum plate was reduced to 78 ℃, but the reduction effect thereof was small compared to the examples. The reason is considered to be that: since the silica particles are dispersed in the resin, the effect of enhancing the heat dissipation property by the surface plasmon resonance is not sufficiently obtained.

< example 7 >

The sample prepared in example 2 was mounted on an electronic component (heat-generating body) of an electronic device shown in fig. 11, and the effect of temperature decrease was examined.

The electronic device 100 shown in fig. 11 includes: an electronic component 101 and a circuit board 102 on which these components are mounted. The sample 103 produced in example 2 was peeled from the base material, and the surface opposite to the side from which the base material was peeled was mounted on the upper portion of the electronic component 101. When the electronic apparatus is operated, the temperature of the electronic part 101 is reduced from 125 ℃ (no sample) to 95 ℃.

< example 8 >

The sample prepared in example 3 was mounted on an electronic component (heat-generating body) of an electronic device shown in fig. 12, and the effect of temperature decrease was examined.

The electronic apparatus 100 shown in fig. 12 includes: an electronic component 101 and a circuit board 102 on which these components are mounted. Further, the periphery of the electronic component 101 is sealed with the resin 104. The sample 103 produced in example 3 was peeled from the base material, and the surface opposite to the side from which the base material was peeled was mounted on the upper portion of the electronic component 101. When the electronic device is operated, the temperature of the electronic part 101 is reduced from 155 ℃ (no sample) to 115 ℃.

< example 9 >

The sample prepared in example 1 was mounted on a heat pipe (heat generating body) as shown in fig. 13, and the effect of temperature decrease was examined.

The heat pipe 22 shown in fig. 13 is a stainless steel pipe (diameter 32mm), and the sample 1 mounted around the heat pipe includes copper particles 11 and a resin 12, and has a structure in which the copper particles 11 are aggregated on the side opposite to the side in contact with the heat pipe 22 to form a metal particle layer. When 90 ℃ water was flowed to the interior of the heat pipe, the surface temperature decreased from 85 ℃ (no sample) to 68 ℃.

All documents, patent applications, and technical specifications described in the present specification are cited and incorporated in the present specification to the same extent as if each document, patent application, and technical specification was specifically and individually described to be incorporated by reference.